1. Technical Field
The present invention relates to a semiconductor circuit, a semiconductor device, a method of diagnosing an abnormality of a wire, and a computer readable medium, and in particular, relates to a semiconductor circuit, a semiconductor device, a method of diagnosing an abnormality of a wire, and a computer readable storage medium, for battery monitoring.
2. Related Art
A battery in which plural batteries (battery cells) are connected in series (lithium ion batteries and the like are concrete examples thereof) is generally used as a battery that has a large capacity and a high output and is used in motor driving and the like of a hybrid automobile or an electric automobile. There are known battery systems that are for monitoring and controlling the voltages of the batteries of such a battery.
A conventional battery monitoring system is structured to include a battery cell group that includes plural battery cells, and a semiconductor circuit that measures and controls the voltages of the battery cells included in the battery cell group.
In the battery monitoring system, cell voltage equalizing processing of the battery cell group (processing that makes the voltage values of the respective battery cells uniform) and charging/discharging control processing (processing that controls the charging and discharging of the respective battery cells), and the like are carried out on the basis of voltage information of the respective battery cells that is obtained from the semiconductor circuit for measurement. In such a battery monitoring system, when disconnection or short circuiting occurs at the wires that connect the battery cells and the semiconductor circuit for measurement, there are cases in which problems arise in the battery monitoring system. In such cases, repair must be carried out, but, when repairing the battery monitoring system, it is necessary to know in advance which of disconnection or short circuiting of a wire has occurred, in consideration of expediency of analysis.
For example, the technique disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2007-10580 and the technique disclosed in JP-A No. 2009-257923 are examples of techniques that diagnose disconnection of wires that connect a battery cell group and a semiconductor circuit for measurement in a battery monitoring system.
A technique of diagnosing disconnection and short circuiting of wires relating to battery cells in such a conventional battery monitoring system is described. FIG. 12 is a circuit diagram showing an example of the schematic structure of the conventional battery monitoring system. A battery monitoring system 100 shown in FIG. 12 is structured to include a battery cell group 112 in which four cells C1 through C4 are connected in series, and a semiconductor circuit 114 for voltage measurement of the battery cell group 112. The semiconductor circuit 114 is structured to include a cell selection SW 120 that selects one battery cell (cell C1 through C4) from the battery cell group 112, and a level shifter 122 that outputs voltage Vout that is obtained by the voltage of the battery cell (cell C1 through C4) selected by the cell selection SW 120 being level-shifted to a voltage of the same potential as the low potential side of the lowest position cell C1.
In the battery monitoring system 100, when measuring the voltage of the cell C1 through C4, at the cell selection SW 120 of the semiconductor circuit 114, the switch corresponding to the potential of the high potential side and the switch corresponding to the potential of the low potential side of the battery cell to be measured (any one of the cells C1 through C4) are turned on, the potential of the high potential side is inputted to the non-inverting terminal of the level shifter 122, the potential of the low potential side is inputted to the inverting terminal, and the difference between the potential of the high potential side and the potential of the low potential side is outputted from the level shifter 122 as output voltage Vout. By comparing that output voltage Vout with a reference voltage, it is judged whether or not the battery cell voltage is maintained at a desired value. Further, on the basis of the results of this judgment, charging/discharging of voltage is carried out on the battery cell by a circuit or the like that is provided separately from the semiconductor circuit 114.
In the battery monitoring system 100, when carrying out abnormality diagnosis that senses disconnection and short-circuiting as abnormalities of the wires relating to the cells C1 through C4, relationships of correspondence (see FIG. 4) between places where disconnection of the respective cells C1 through C4 (wires V1 through V4) occurs and the output voltage Vout outputted from the level shifter 122, and relationships of correspondence (see FIG. 5) between places where short circuiting arises at the respective cells C1 through C4 (the wires V1 through V4) and the output voltage Vout outputted from the level shifter 122, are obtained in advance. One of the cells C1 through C4 is successively selected at the cell selection SW 120, and, on the basis of the output voltage Vout from the level shifter 122 and the aforementioned relationships of correspondence, it is sensed which of disconnection or short circuiting has occurred, and the place where the disconnection or short circuiting has occurred is sensed.
However, in the aforementioned abnormality diagnosing technique, as shown in FIG. 4 and FIG. 5, the detection results of disconnection and the detection results of short circuiting are the same at the battery cell of the highest position (the highest potential side) and the battery cell of the lowest position (the lowest potential side), and disconnection and short circuiting cannot be distinguished. Therefore, there is the problem that disconnection and short circuiting of the wires relating to the battery cells cannot be diagnosed appropriately.